Hello,

I am currently using Stata to replicate an analysis with complex svy data to obtain weighted prevalence estimates and Clopper Pearson (exact) confidence intervals by demographic characteristics for data validation purposes. The original analysis was carried out in SAS-callable Sudaan. I noticed that the CIs are off by varying degrees, while all other output matches exactly, including prevalence estimates, as well as PRs and their corresponding CIs.

My question is: why might the resulting CIs for proportions differ somewhat between Stata and SAS output? The difference seems to be greater when there are a smaller number of observations in the subpopulation.

Here is an example of the Stata code I am using to obtain prevalence estimates and exact CIs for parent physical health by child's age (dichotomised):

Code:
svy, subpop(if include == 1 & age == 0): prop parent_physhealth, citype(exact)
svy, subpop(if include == 1 & age == 1): prop parent_physhealth, citype(exact)
Thank you so much in advance,
Helena